The present invention relates to the production of synthetic yarns in which subsequent to melt spinning the yarn is drawn and twisted on an apparatus sometimes hereinafter referred to as a drawtwister. In particular, the invention is directed to a string-up and cut-down device on a drawtwister.
The production of synthetic yarns often involves a two step process, that is, first, unoriented filaments are melt spun and wound onto bobbins; second, a creel of these bobbins is used to supply a drawtwister which draws or orients the filaments, twists them together and winds the resultant yarn onto pirns.
A method of producing synthetic yarns in which the filaments are melt spun, drawn, twisted and wound onto pirns without the intermediate step of bobbin winding has been shown to be possible and to have the advantages of reducing labor requirements and of improving yarn quality. However, conventional drawtwisters are designed to operate with a creel of passive bobbins and are not designed to handle a continuously flowing supply during periods when the yarn is not being wound onto the pirn.
It is an object of this invention to provide a means with which a conventional drawtwister, employing a conventional ring twisting technique, may be adapted to accommodate a continuous supply of yarn.
It is also an object of this invention to provide a string-up apparatus which may be operated manually on an individual position of a drawtwister or automatically and simultaneously over all the drawtwister positions while the drawtwister is running with a continuous supply of yarn.
It is a further object of this invention to provide a means by which a drawtwister may be left strung up and running during doffing.
It is yet another object of this invention to provide an automatic cut-down means which may be operated manually on individual positions or automatically and simultaneously over all positions of the drawtwister being adapted to stop the yarn from winding onto the pirn without interrupting continuous supply which remains running through the drawtwister.